1. Field of the Invention
The present invention generally relates to a semiconductor substrate processing apparatus; particularly to a semiconductor substrate transfer apparatus for carrying in/out a semiconductor wafer between a storing container and a processing container.
2. Description of the Related Art
In a semiconductor processing apparatus, a semiconductor wafer normally has to be transferred between plural separate containers inside the apparatus in order to deliver the wafer from a storing container to a processing container in which a target process is performed. As this type of mechanism for transferring a semiconductor wafer, a transfer robot is widely known. In conventional semiconductor processing apparatuses, there are many different types of transfer robots having various shapes and motion forms in order to meet the apparatuses' purposes and requirements.
In recent years, in semiconductor production, a throughput of a semiconductor processing apparatus (the number of wafers processed per unit time) has become a matter of great concern. In order to increase a throughput, a transfer robot having a mechanism of transferring plural wafers all at once has been realized. This method transfers plural pieces being held on a portion of a robot for holding a wafer, which is called an end effector, at one time by adjusting a width of the end effector to a slot interval of a storing container and placing plural wafers on the end effector in a perpendicular direction. This type of transfer robot is disclosed in, for example, Japanese National Phase Publication No. 2001-501597 (Patent Reference 1)
In this type of apparatus, if a slot interval of a wafer-storing container and a slot interval of a container to which a wafer is transferred differ, it becomes necessary to add a mechanism of adjusting an interval in a perpendicular direction of each end effector while wafers are being transferred.
As another type of transfer robot, there is a type whose end effector holds only one wafer but which also has a different independent end effector, in which a motion to unload a wafer from a storing container using one end effector and a motion to load a wafer which was unloaded from the storing container prior to being loaded using the other end effector are performed simultaneously. This type of transfer robot is called a dual-arm robot and can realize a throughput twice the one realized by a single-arm robot.
Furthermore, as still another type of transfer robot, a type combining the above-mentioned method of transferring plural wafers all at once and the dual-arm method is disclosed in, for example, Japanese Patent Laid-open No. 1995-106402 (Patent Reference 2).